Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, January 24th 2016 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Today a CONSIDERABLE avalanche danger exists in the Alpine and at Treeline where triggering a fresh windslab 8”-20” thick will be likely on steep wind loaded features. Careful snowpack evaluation and cautious routefinding will be essential in areas that have experienced active windloading. Be on the look out for shooting cracks and avoid steep wind-loaded features where trigging even a small slab could have high consequences. In addition pay attention for slopes with glide cracks and do your best to avoid this unpredictable hazard.

A LOW avalanche danger exists below 1000’ where triggering an avalanche is unlikely.

If you are thinking of going to Summit Lake, be aware that different avalanche hazards exist within the snowpack. Click HERE to read the most current Summit Lake Summary. 

 Show the Complete North American Avalanche Danger Scale
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Special Announcement

Monday, January 25th, 7-8 pm: Come to the Blue and Gold Board Shop for a FREE Avalanche Awareness class taught by CNFAIC forecaster Heather Thamm. For more details click here: HERE. Know Before You Go!

Avalanche Problem 1

Yesterday afternoon Easterly ridgetop winds suddenly increased into the 20’s mph with gusts in the 40’s mph creating 6” tender wind slabs. A small natural avalanche was observed on a Northwest aspect on Superbowl, near Corn Bicuit, and shortly after a skier triggered a wind slab on a steep convexity at 2300’ in this zone. Overnight another 6” of snow fell and strong Easterly winds continued. Today winds and precipitation are expected to decrease, before another burst of wind and snow arrive late this afternoon/early evening.

Today wind slabs 8”-20” will be easily triggered on wind loaded terrain features such as below ridgetops and on convex rollovers. These slabs will be more developed on Western aspects (Southwestern – Western – Northwestern.) Areas such as the Western facing bowls of Seattle Ridge will be suspect in the mid elevation band (below 2500’.) Pay attention for cross-loading on all other aspects.

Managing this hazard will be possible by choosing low angle terrain and sticking to routes that are scoured and wind eroded. Be on the lookout for denser snow on top of weaker snow below; shooting cracks will be an instant sign that this snow is tender. Both hard and soft wind slabs could be present today, and both have the potential to fracture above you. Luckily this is a surface instability issue, meaning these slabs will be isolated to wind loaded zones, and triggering an older deeper layer below is unlikely. However that being said these slabs are expected to be touchy and even a small isolated slab in the wrong place can have high consequences. 

Debris from a skier triggered slab on Superbowl, Northwest aspect, near Corn Biscuit yesterday afternoon. This fresh wind slab was 6" deep, 40' wide and ran approximately 150'. 


Alaska Avalanche School Level 2 class dug a pit in an area where they observed a 20' shooting crack near Common bowl on Tincan. Click HERE for observation. 


Avalanche Problem 2

Glides continue to slowly open and every once in a while one will release. There is no discernable pattern to predict their failure as they tend to fail naturally and on their own schedule. Warm temperatures can trigger them and so can cooling temperatures. A new glide avalanche was seen on East Seattle Ridge yesterday at (~1300) and one released on Sharks Fin (South facing ~2,000') mid week. Since glide cracks can spontaneously release at any time, it is best to avoid, or do your best to limit time under them. With questionable visibility again today, it may be difficult to identify glide cracks. 

Small glide release seen yesterday along Seattle Ridge at ~1300'. Timing of release is unknown. Many large glide cracks can still be seen all along Seattle Ridge East face.

Mountain Weather

Yesterday scatted snow flurries moved through Turnagain Pass and light rain fell below 1000’ in Girdwood. Winds picked up around 3pm and increased into the 30’s mph with gusts in the 60’s by early evening. Overnight 6” of snow was recorded at Center Ridge Weather station combined with strong winds.

Today winds are expected to decrease to 15-30mph through early afternoon before another burst of moisture and strong winds arrive early this evening. Expect a few inches of new snow above 1500’, and light rain at lower elevations due to warmer temperatures.

Overnight another 6-10” of snow combined with strong Easterly winds is expected in the Alpine. Rain/snow  line is expected to remain around 1500’


PRECIPITATION 24-hour data (6am - 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 30  0.4  89 
Summit Lake (1400') 32   0 26 
Alyeska Mid (1700') 32  .53  73 


RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 23  NE  23  63 
Seattle Ridge(2400') 26   n/a   n/a  n/a 

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Oct 05, 2019 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.

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